A novel technique to search for FG's progenitors is the use of strong gravitational lensing in galaxy groups. [1]} investigated the fraction of FGs in lensed and non-lensed galaxy groups, finding that the fraction of FGs is larger in lensed systems (13% versus 3%). They also identified 12 possible FG progenitors, that were later investigated in details in [2]} using Chandra and the Hubble Space Telescope. Their results showed that the X-ray temperatures of the candidate progenitors are higher than those of the control sample. They also find hints of differences in the LFs of FGs and non-FGs, but these differences are erased when BCGs are removed. Finally, [3]} studied the strong-lensed FG J0454-0309, that is found behind a well-studied non-fossil poor cluster. Their analysis support a scenario in which the fossil system is falling into the poor cluster and where the central galaxy of the FG will become the brightest galaxy of the new system.
